[lldb] [llgs] Send process output asynchronously in non-stop mode

Introduce a new %Stdio notification category and use it to send process
output asynchronously when running in non-stop mode.  This is an LLDB
extension since GDB does not use the 'O' packet for process output,
just for replies to 'qRcmd' packets.

Using the async notification mechanism implies that only the first
output packet is sent immediately to the client.  The client needs
to request subsequent notifications (if any) using the new vStdio packet
(that works pretty much like vStopped for the Stop notification queue).

The packet handler in lldb-server tests is updated to handle the async
stdio packets in addition to the regular O packets.  However, due
to the implications noted above, it can only handle the first output
packet sent by the server.  Subsequent packets need to be explicitly
requested via vStdio.

Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.llvm.org/D128849

1 files changed, 5 insertions, 0 deletions

diff --git a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.h b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.h
index 47e8a78..3d67032 100644
--- a/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.h
+++ b/lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.h
@@ -117,6 +117,7 @@ protected:
   bool m_thread_suffix_supported = false;
   bool m_list_threads_in_stop_reply = false;
   bool m_non_stop = false;
+  std::deque<std::string> m_stdio_notification_queue;
   std::deque<std::string> m_stop_notification_queue;
 
   NativeProcessProtocol::Extension m_extensions_supported = {};
@@ -247,6 +248,10 @@ protected:
 
   PacketResult Handle_QNonStop(StringExtractorGDBRemote &packet);
 
+  PacketResult HandleNotificationAck(std::deque<std::string> &queue);
+
+  PacketResult Handle_vStdio(StringExtractorGDBRemote &packet);
+
   PacketResult Handle_vStopped(StringExtractorGDBRemote &packet);
 
   PacketResult Handle_vCtrlC(StringExtractorGDBRemote &packet);